Dispersive shock waves (DSWs) are fascinating wave phenomena occurring in media when nonlinearity overwhelms dispersion (or diffraction). Creating DSWs with low generation power and realizing their active controls is desirable but remains a longstanding challenge. Here, we propose a scheme to generate weak-light DSWs and realize their manipulations in an atomic gas involving strongly interacting Rydberg states under the condition of electromagnetically induced transparency. We show that for a two-dimensional Rydberg gas, weak nonlocality of optical Kerr nonlinearity can significantly change and induce a singular behavior of the edge speed and hence an instability of the DSWs, which, however, can be suppressed by increasing the degree of the Kerr nonlocality. We also show that in a three-dimensional Rydberg gas, DSWs can be created and propagate stably when the system works in the intermediate nonlocality regime. Different from the DSWs reported before, the DSWs found here have extremely low generation power. Moreover, such DSWs can be actively controlled; in particular, they can be stored and retrieved with high efficiency and fidelity through switching off and on a control laser field. The results reported here are useful not only for unveiling intriguing physics of DSWs but also for finding promising applications of nonlinear and nonlocal Rydberg media.
Dispersive shock waves (DSWs) are fascinating wave phenomena occurring in media when nonlinearity overwhelms dispersion (or diffraction). Creating DSWs with low generation power and realizing their active controls is desirable but remains a longstanding challenge. Here, we propose a scheme to generate weak-light DSWs and realize their manipulations in an atomic gas involving strongly interacting Rydberg states under the condition of electromagnetically induced transparency. We show that for a two-dimensional Rydberg gas, weak nonlocality of optical Kerr nonlinearity can significantly change and induce a singular behavior of the edge speed and hence an instability of the DSWs, which, however, can be suppressed by increasing the degree of the Kerr nonlocality. We also show that in a three-dimensional Rydberg gas, DSWs can be created and propagate stably when the system works in the intermediate nonlocality regime. Different from the DSWs reported before, the DSWs found here have extremely low generation power. Moreover, such DSWs can be actively controlled; in particular, they can be stored and retrieved with high efficiency and fidelity through switching off and on a control laser field. The results reported here are useful not only for unveiling intriguing physics of DSWs but also for finding promising applications of nonlinear and nonlocal Rydberg media.
X waves are a special type of wave packet that can maintain their transverse profile of X shape during propagation, and they are of much interest for the study of fundamental physics and practical applications. Here we present a scheme to generate nonlinear X waves and realize their active control by using a cold gas of Rydberg atoms via electromagnetically induced transparency (EIT). We show that, due to the EIT effect contributed by a control laser field and the strong, nonlocal Kerr nonlinearity contributed by Rydberg-Rydberg interaction between atoms, the system supports high-dimensional, nonlocal, and nonlinear optical X waves, which have low propagation loss, ultraslow propagation velocity, and ultralow generation power. We also show that the stability domain of such X waves can be greatly enlarged by increasing the nonlocality degree of the Kerr nonlinearity, and their motion trajectory can be manipulated by using an external magnetic field. Our study opens a route for generating and controlling nonlocal ultraslow nonlinear optical X waves, which may have promising applications in optical information processing and transmission.
Realizing single light bullets and vortices that are stable in high dimensions is a long-standing goal in the study of nonlinear optical physics. On the other hand, the storage and retrieval of such stable high dimensional optical pulses may offer a variety of applications. Here we present a scheme to generate such optical pulses in a cold Rydberg atomic gas. By virtue of electromagnetically induced transparency, strong, long-range atom-atom interaction in Rydberg states is mapped to light fields, resulting in a giant, fast-responding nonlocal Kerr nonlinearity and the formation of light bullets and vortices carrying orbital angular momenta, which have extremely low generation power, very slow propagation velocity, and can stably propagate, with the stability provided by the combination of local and the nonlocal Kerr nonlinearities. We demonstrate that the light bullets and vortices obtained can be stored and retrieved in the system with high efficiency and fidelity. Our study provides a new route for manipulating high-dimensional nonlinear optical processes via the controlled optical nonlinearities in cold Rydberg gases.
We investigate the generation of optical shock waves in strongly interacting Rydberg atomic gases with a spatially homogeneous dissipative potential. The Rydberg atom interaction induces an optical nonlocal nonlinearity. We focus on local nonlinear ( R b ≪ R 0 ) and nonlocal nonlinear ( R b ∼ R 0 ) regimes, where R b and R 0 are the characteristic length of the Rydberg nonlinearity and beam width, respectively. In the local regime, we show spatial width and contrast of the shock wave change monotonically when increasing strength of the dissipative potential and optical intensity. In the nonlocal regime, the characteristic quantity of the shock wave depends on R b / R 0 and dissipative potential nontrivially and on the intensity monotonically. We find that formation of shock waves dominantly takes place when R b is smaller than R 0 , while the propagation dynamics is largely linear when R b is comparable to or larger than R 0 . Our results reveal nontrivial roles played by dissipation and nonlocality in the generation of shock waves, and provide a route to manipulate their profiles and stability. Our study furthermore opens new avenues to explore non-Hermitian physics and nonlinear wave generation and propagation by controlling dissipation and nonlocality in the Rydberg media. Published by the American Physical Society 2024
Quantum reflection refers to a nonvanishing reflection probability in the absence of a classically turning point. Much attention has been paid to such reflections due to their fundamental, intriguing physics and potential practical applications. Here we propose a scheme to realize a quantum reflection of nonlocal nonlinear optical beams in a cold Rydberg atomic gas via electromagnetically induced transparency working in a dispersion regime. Based on the long-range interaction between Rydberg atoms, we found that the system supports low-power nonlocal optical solitons. Such nonlocal solitons can display a sharp transition between reflection, trapping, and transmission when scattered by a linear attractive potential, created by gate photons stored in another Rydberg state. Different from conventional physical systems explored up to now, the quantum reflection of the nonlocal optical solitons in the Rydberg atomic gas exhibits interesting anomalous behavior, which can be actively manipulated by tuning the incident velocity and intensity of the probe field, as well as the nonlocality of the Kerr nonlinearity inherent in the Rydberg atomic gas. The results reported here are not only useful for developing Rydberg nonlinear optics but also helpful for characterizing the physical property of the Rydberg gas and for designing novel nonlinear optical devices.
Light bullets (LBs) are localized nonlinear waves propagating in high spatial dimensions.Finding stable LBs and realizing their control are desirable due to the interesting physics and potential applications.Here, we show that nonlocal LBs generated in a cold Rydberg atomic gas via the balance among the dispersion, diffraction, and giant nonlocal Kerr nonlinearity contributed by long-range Rydberg-Rydberg interaction can be actively manipulated by using a weak gradient magnetic field.Nonlocal LBs are generated by a balance among dispersion, diffraction, and large nonlocal Kerr nonlinearities contributed by long-range Rydberg-Rydberg interactions.Here, we find that active manipulation can be achieved by weak gradient magnetic fields in cold Rydberg atomic gases.Especially, the LBs may undergo significant Stern-Gerlach deflections, and their motion trajectories can be controlled by adjusting the magnetic-field gradient.The results reported here are helpful not only for understanding unique properties of LBs in nonlocal optical media but also for finding ways for precision measurements of magnetic fields.
We propose a scheme to realize parity-time (PT) symmetry and nonlocal optical solitons in a cold Rydberg atomic system with electromagnetically induced transparency. We show that a two-dimensional (2D) periodic optical potential with PT symmetry can be obtained for the propagation of probe laser field by using an incoherent population pumping between two low-lying levels and spatial modulations of control and assistant laser fields. We also show that, based on the giant nonlocal Kerr nonlinearity originated from the strong, long-range atom-atom interaction, the system supports 2D nonlocal gap solitons with very low light intensity. In particular, we find that the degree of the nonlocality of the Kerr nonlinearity, which can be actively tuned in our system, can be used to manipulate the phase transition of the PT symmetry and the behavior of the nonlocal optical solitons. Our study opens a route for developing non-Hermitian nonlinear optics, especially for realizing and controlling high-dimensional weak-light optical solitons through adjustable PT symmetry and giant nonlocal optical nonlinearity.